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(5.1) Field of the Invention
The present invention relates generally to ink-jet printhead fabrication and, more specifically to making a re-usable mandrel to electroform orifice sheets with a defined, tapered profile.
(5.2) Description of Related Art
The art of ink-jet technology is relatively well developed. Commercial products such as computer printers, graphics plotters, copiers, and facsimile machines employ ink-jet technology for producing hard copy. The basics of this technology are disclosed, for example, in various articles in the Hewlett-Packard Journal, Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol. 39, No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 45, No. 1 (February 1994) editions. Ink-jet devices are also described by W. J. Lloyd and H. T. Taub in Output Hardcopy [sic] Devices, chapter 13 (Ed. R. C. Durbeck and S. Sherr, Academic Press, San Diego, 1988). Also, many publications describe the details of common techniques used in the fabrication of thin film devices and integrated circuits that can be generally employed in the fabrication of complex, three-dimensional, silicon wafer substrate structures; see e.g., Silicon Processes, Vol. 1-3, copyright 1995, Lattice Press, Lattice Semiconductor Corporation (assignee herein), Hillsboro, Oreg. Moreover, the individual steps of such a process can be performed using commercially available fabrication machines. The use of such machines and common fabrication step techniques will be referred to hereinafter as simply: xe2x80x9cin a known manner.xe2x80x9d As specifically helpful to an understanding of the present invention, approximate technical data are disclosed herein based upon current technology; future developments in this art may call for appropriate adjustments as would be apparent to one skilled in the art.
The state of the art is continually developing to improve the quality of the fundamental dot matrix form of printing intrinsic to ink-jet technology. Current products have achieved print densities of 1200 dots-per-inch (xe2x80x9cDPIxe2x80x9d), achieving print quality comparable to the more expensive laser printers. To that end, thin-film technology has been employed to produce precision components such as orifice plates, fine mesh ink filters, and the like, for ink-jet printheads.
For example, ink-jet pens can utilize an orifice plate generally formed on a thin-film mandrel. The mandrel can consist of a glass plate coated with a conductive film. Non-conductive discs are defined on the surface of the conductive film for determining the location and size of the orifices. Generally, the discs are about three times the diameter of the target hole size. Looking to FIG. 1 (Prior Art), the profile of an electroformed ink-jet nozzle is described by a relationship between the exit bore diameter, Dbore, the mandrel pad (non-conducting region) diameter, Dpad, and the thickness, T, of the electroformed sheet:
Dbore=Dpadxe2x88x922Txe2x80x83xe2x80x83Equation 1.
The orifice size is determined by carefully controlling the electroplating parameters (current, timing, and the like) for forming an orifice plate on the mandrel. Therefore, a variation in these parameters will directly affect the size of the orifices. Moreover, if a thicker orifice plate is needed, it is necessary to increase the disc size. Manufacturing tolerances limit such disc dimensioning, resulting in a decreased orifice diameter if the thickness of the orifice plate increases over the disc size tolerance.
One example of an improved METHOD OF MAKING INK-JET COMPONENTS is described in U.S. Pat. No. 5,560,837, Oct. 1, 1996, by Trueba (assigned to the common assignee herein and incorporated herein by reference). Trueba shows a process for fabricating a thin-film structure using a transparent substrate. A first structure, such as a ring having a central pillar, is formed of a conductive material on a surface of the substrate. A photoresist material pillar is formed on top of the conductive material central pillar by exposure through the transparent material.
Generally, state of the art orifice plating mandrel is two-dimensional, meaning that the profile of the orifice assumes a curved shape while the electro-deposited material grows. This is disadvantageous because the ink drop exit bore diameter depends directly on the plating thickness as a function of position. As a result, the bore diameter standard deviation is large across an orifice sheet.
As the state of the art progresses, ink-jet orifice bore diameter tends to decrease. Bore diameter standard deviation for tolerance needs to be reduced. Moreover, bore profiles need to be more accurately engineered so that pen performance can be optimized.
In its basic aspect, the present invention provides a process for fabricating a mandrel including: forming a first structure having a substantially planar electrically conductive surface having a plurality of electrically non-conductive mandrel associated first features affixed distributively across said conductive surface; using said first structure, forming a complementary second structure such that said complementary second structure has a plurality of second features complementary of said first features; and using said second structure, forming the mandrel having third features wherein said third features define shape, location and geometry of features of an electroform created using said mandrel.
In another aspect, the present invention provides a process for fabricating an ink-jet printhead mandrel including: forming a first structure having a substantially planar metalized first surface having a plurality of dielectric first features distributed across said first surface; using said first structure, forming a complementary second structure such that said complementary second structure has a plurality of second features complementary of said first features; and using said second structure, forming the mandrel having third features wherein said third features define shape, location and geometry of features of an inkjet printhead to be electroformed using said mandrel.
In still another aspect, the present invention provides an ink-jet printhead mandrel including: a glass substrate having a plurality of glass-formed mandrel features for electroforming an ink-jet printhead construction hereon; a metal layer superjacent the glass substrate conforming to said features; and a dielectric layer superjacent the metal layer only on and conforming to said features.
The foregoing summary is not intended to be an inclusive list of all the aspects, objects, advantages, and features of the present invention nor should any limitation on the scope of the invention be implied therefrom. This Summary is provided in accordance with the mandate of 37 C.F.R. 1.73 and M.P.E.P. 608.01(d) merely to apprise the public, and more especially those interested in the particular art to which the invention relates, of the nature of the invention in order to be of assistance in aiding ready understanding of the patent in future searches. Objects, features and advantages of the present invention will become apparent upon consideration of the following explanation and the accompanying drawings, in which like reference designations represent like features throughout the drawings.